﻿#!/usr/bin/env python

import sys, os, time, atexit, platform, traceback, logging,signal

class Daemon:
    """
    A generic daemon class.
    
    Usage: subclass the Daemon class and override the run() method
    """
    def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null',home_dir='.',umask=0,verbose=1):
        self.stdin = stdin
        self.stdout = stdout
        self.stderr = stderr
        self.pidfile = pidfile
        self.home_dir = home_dir
        self.umask = umask
        self.verbose = verbose #调试开关
        self.daemon_alive = True 
    
    def daemonize(self):
        """
        do the UNIX double-fork magic, see Stevens' "Advanced 
        Programming in the UNIX Environment" for details (ISBN 0201563177)
        http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16
        """
        try: 
            pid = os.fork() 
            if pid > 0:
                # exit first parent
                sys.exit(0) 
        except OSError, e: 
            sys.stderr.write(u"fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
            sys.exit(1)
    
        # decouple from parent environment
        os.chdir(self.home_dir) 
        os.setsid() 
        os.umask(self.umask)
        # do second fork
        try: 
            pid = os.fork() 
            if pid > 0:
                # exit from second parent
                sys.exit(0) 
        except OSError, e: 
            sys.stderr.write(u"fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
            sys.exit(1) 
    
        # redirect standard file descriptors
        sys.stdout.flush()
        sys.stderr.flush()
        si = file(self.stdin, 'r')
        so = file(self.stdout, 'a+')
        se = file(self.stderr, 'a+', 0)
        os.dup2(si.fileno(), sys.stdin.fileno())
        os.dup2(so.fileno(), sys.stdout.fileno())
        os.dup2(se.fileno(), sys.stderr.fileno())
        def sig_handler(signum, frame):  
            self.daemon_alive = False  
        signal.signal(signal.SIGTERM, sig_handler)  
        signal.signal(signal.SIGINT, sig_handler) 

        if self.verbose >= 1:  
            print 'daemon process started ...'
        # write pidfile
        atexit.register(self.delpid)
        pid = str(os.getpid())
        file(self.pidfile, 'w+').write("%s\n" % pid)
    
    def delpid(self):
        os.remove(self.pidfile)


    def get_pid(self):
        try:
            pf = file(self.pidfile, 'r')
            pid = int(pf.read().strip())
            pf.close()
        except IOError:
            pid = None
        except SystemExit:
            pid = None
        return pid

    def start(self):
        """
        Start the daemon
        """
        # Check for a pidfile to see if the daemon already runs
        if self.verbose >= 1:  
            print 'ready to starting ......'
        pid = self.get_pid()
        if pid:
            message = "pidfile %s already exist. Daemon already running?\n"
            sys.stderr.write(message % self.pidfile)
            sys.exit(1)
        
        # Start the daemon
        self.daemonize()
        self.run()

    def stop(self):
        """
        Stop the daemon
        """
        # Get the pid from the pidfile
        if self.verbose >= 1:  
            print 'stopping ...' 
        pid = self.get_pid()
    
        if not pid:
            message = "pidfile %s does not exist. Daemon not running?\n"
            sys.stderr.write(message % self.pidfile)
            return  # not an error in a restart

        # Try killing the daemon process    
        try:
            while 1:
                os.kill(pid, signal.SIGTERM)
                time.sleep(0.1)
        except OSError, err:
            err = str(err)
            if err.find("No such process") > 0:
                if os.path.exists(self.pidfile):
                    os.remove(self.pidfile)
            else:
                print str(err)
                sys.exit(1)
            if self.verbose >= 1:  
                print 'Stopped!'

    def restart(self):
        """
        Restart the daemon
        """
        self.stop()
        self.start()

    def is_running(self):
        pid = self.get_pid()
        return pid and os.path.exists('/proc/%d' % pid)

    def run(self):
        """
        You should override this method when you subclass Daemon. It will be called after the process has been
        daemonized by start() or restart().
        """

class MyDaemon(Daemon):
    def __init__(self,pid, func):
        Daemon.__init__(self, pid)
        self.__func = func
    def run(self):
        self.__func(True)

        
def log_uncaught_exceptions(ex_cls, ex, tb):
    logging.critical(''.join(traceback.format_tb(tb)))
    logging.critical('{0}: {1}'.format(ex_cls, ex))

def run(pid,func):
    sys.excepthook = log_uncaught_exceptions
    if platform.system() == "Linux":
        daemon = MyDaemon(pid,func)
        if len(sys.argv) == 2:
            if 'start' == sys.argv[1]:
                daemon.start()
            elif 'stop' == sys.argv[1]:
                daemon.stop()
            elif 'restart' == sys.argv[1]:
                daemon.restart()
            elif 'console' == sys.argv[1]:
                func(False)    
            elif 'status' == sys.argv[1]:
                alive = daemon.is_running()
                if alive:
                    print 'process [%s] is running ......' % daemon.get_pid()
                else:
                    print 'daemon process stopped'      
            else:
                print "Unknown command"
                sys.exit(2)
            sys.exit(0)
        else:
            print u"usage: %s start|stop|restart|console" % sys.argv[0]
            sys.exit(2)
    else:
        func(False)